1. Field of the Invention
The present invention relates to a blasting medium picking-apart device, in particular, to a blasting medium of sponge fragments formed of abrasives stuck within a porous elastic body.
2. Description of the Related Art
Blasting is required as a pre-construction work in recoating a coated wall, and includes grinding the coating on the wall surface and roughening the coated surface for a surface preparation.
Such blasting work is performed by a sand blasting method such as that described in Japanese Patent Application Laid-Open No. 9-109029. Sand blasting is a construction method including the steps of hurling jetting sands (sands: blast materials) from a nozzle by using high speed air to impinge hit against them to a coated surface, and grinding and roughening a coated film on the coated surface with the impulsive force of the sands.
However, the sand blasting had a problem that the blast materials are bounced back with a strong force, which spreads coarse particulates in all directions. There is another problem that a worker who operates a nozzle has to be heavily covered up with wears to protect himself/herself from the blast materials which are bounced back with a strong force, and this affects the workability. Moreover, the spreading coarse particulates block the view of a worker, which makes it difficult to form a coating with a uniform quality.
As solutions to these problems, conventionally, a construction method which uses a blasting medium of sponge fragments formed of abrasives stuck within a porous elastic body, a so-called sponge blasting, has been known.
According to the sponge blasting, blasting medium are jetted from a nozzle by using high speed air to hit against a coated surface, the blasting medium becomes flat, which causes the abrasives attached to the blasting medium to directly hit against the coated surface at a high speed. This enables the grinding and removing a coated film on the surface to be achieved, as in the sand blasting. In the sponge blasting, the coarse particulates, which are otherwise airborne, are drawn into the sponge and fall down with the sponge, thereby advantageously the spreading of coarse particulates is reduced. Furthermore, there is another advantage that the sponge absorbs the bounce, and this considerably reduces the coarse particulates which bounce back, and a worker who operates a nozzle do not have to be heavily covered up with wears.
Japanese Patent Application Laid-Open No. 2002-28466 discloses a coated fertilizer treatment apparatus for stirring and dispersing granular solid particles by using a porous plate and two rotary vanes including an upper vane and a lower vane.